This invention relates to air filters, and more particularly to an improved air filter providing a molded-in-place radial seal.
Pleated paper filter elements are used on over-the-road trucks, agricultural, automotive and off-highway equipment for preventing dirt and dust from entering the engine with the incoming air supply. A popular type of air filter element is that which provides a radial seal, wherein a seal, usually on the inside of the open end of the filter, tightly engages a pipe or conduit which supplies air to the engine. In most cases, the air is drawn into the housing and through the air cleaner element in an outside-in direction. Contaminant in the air stream is removed by flowing through the pleated paper media whose ends are encapsulated into a close molded end cap at one side and an open molded end cap at the other side. The seal at the open end cap side is established by compressing or stretching an inward facing radial gasket made of rubber-like material around the outward facing surface of a cylindrical shaped outlet member of the housing.
U.S. Pat. No. 4,720,292 discloses an air filter element in which both end caps are molded. The radial seal filter on the open molded end cap is provided by the soft rubbery material which forms the end cap. The gasket portion itself is supported on the inner liner of the media pack. An advantage of the filter element is said to be the fact that the radial seal element is supported on the inner liner and the forces on the inner liner (such as those which result when the filter element is restricted) deflect the inner liner inwardly and increase the pressure on the radial seal. A filter element constructed according to these teachings has certain drawbacks, not the least of which is the fact that sealing force of the radial seal gasket is directly proportional to the forces exerted on the gasket by the inner liner. Thus, plugged filter conditions, which can distort the inner liner, can cause uneven forces on the gasket. The filter is also weak at the closed end cap side. The urethane potting compound from which the end cap is made can tend to deflect severely when subjected to relatively high pressure differentials.
U.S. Pat. No. 5,484,466 shows another air filter with a radial seal. The radial seal in the ""466 patent is a separately formed nitrile element having a portion which is encapsulated into the formed end cap. The gasket element itself, while carried by the formed end cap, is a separate element and provides an independent radial seal. The structure shown in the ""466 patent, however, suffers from the problem of being somewhat higher in cost than other filter elements due to the separately formed gasket member. The structure also leads to a filter which is somewhat heavier in weight and higher in cost.
A general aim of the present invention is to provide a cylindrical air filter with a formed-in-place radial seal gasket in which the formed-in-place gasket is substantially isolated from forces normally imposed on the inner liner.
It is an object to provide a radial seal air filter in which the radial seal is isolated from the inner liner, but which is lighter in weight and lower in cost than other isolated designs.
A further and detailed object is to provide a formed-in-place radial seal in an air filter which is closely centered with respect to the filter media pack, but which provides a sealing force which is substantially independent of the forces imposed on the media pack and its liners.
A resulting object is to provide a filter with a radial seal which has excellent seal integrity in high and low temperature extremes and under vibration conditions normally encountered.
Other objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention.
In the drawings:
FIG. 1 is a cross-sectional view taken axially through an air filter unit equipped with a filter element constructed in accordance with the invention;
FIG. 2 is a perspective drawing of a filter constructed in accordance with the present invention;
FIG. 3 is a sectional view taken generally along the lines 3xe2x80x943 of FIG. 2;
FIG. 4 is a partial sectional view in enlarged scale of the region of FIG. 3 identified by the circle 4;
FIG. 5 is a perspective view showing an insert ring of the embodiment of FIG. 2;
FIG. 6 is an enlarged sectional view of the insert ring taken generally along the line 6xe2x80x946 of FIG. 5;
FIG. 7 is a diagram showing a mold for forming the gasketed open end cap of the filter of FIG. 2;
FIG. 8 is a diagram showing the left half of the mold of FIG. 7 and illustrating aspects of the molding operation for forming the gasketed end cap; and
FIG. 9 is a partial diagram showing a portion of the closed end cap of the filter of FIG. 2 and showing, on an enlarged scale, the area designated by the circle 9 of FIG. 3.
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.